Apparatus for producing waves in fluid media



F. W. CRAWFORD ETAL 2,568,186

APPARATUS FOR PRODUCING WAVES IN FLUID MEDIA Filed May :5, 1948 INVENTOR. J.S.KIRBY SMITH EW.CRAW FORD Patented Sept. 18, 1951 Francis Weldon Crawford, Bartlesville, kla., and

John S. xirby-smithroak Ridge, Tenn., assignors to Phillips Petroleum Company, a corporation of Delaware Application May 3, 1948, Serial No. 24,808

2 Claims. (01. 177-886) This invention relates to a method of productive wave motion in a fluid medium. In another aspect, it relates to apparatus for producing waves of supersonsic frequencies ingas or liquid media.

'Prior supersonsic wave generators have ordinarily utilized a member vibrating at supersonic frequencies which was in direct contact with the medium through which the supersonic waves were to be transmitted. The amplitude of vibration of the member was very small and, ac-

cordingly, the intensity of the resulting superin certain sonic waves was not as high as desired applications.

In accordance with our invention, the vibrating member is utilized to modulate a stream of fluid as it is discharged from an orifice rather than to directly create the supersonic waves in the fluid medium through which they are propagated. In this way, the intensity of the waves can be considerably increased and, further, the intensity is readily controllable by varying the velocity with which the fluid passes through the orifice. This is accomplished, in accordance with the invention; by forming at least a portion of the orifice of magnetostrictive material and causing such magnetostrictive material to vibrate at supersonic frequencies to effect corresponding variations in the size of the orifice. As a result,

wave motion is produced in the fluid discharged :0

through the orifice which wave motion is of supersonic frequencies.

It is an object of the invention to provide an improved method of and apparatus for producing wave motion in a fluid medium.

It is an object of the invention to provide apparatus which is simple to construct, economical to operate, and reliable in operation.

Various other objects, features and advantages of the invention will become apparent from the 40 following detailed description taken in' conjunction with the appended drawings, in which Figure 1 is a front elevational view of the apparatus with a portion of the coil broken away;

Figure 2 is a sectional view taken along the a line 2-2 of Figure 1; and

Figure 3 is a vertical sectional view of a modification of the invention.

Referring now to the drawings in detail, and

particularly to Figure l, the wave generator com- 50 prises a reservoir iii to which a fluid, such as air, may be fed under pressure-by a conduit Ii. The reservoir i0 is defined by a cylindrical structure it formed of a large number of stacked concenformed therein and these slots are aligned so as I to form a slot-like orifice ll extending lengthwise of the cylindrical structure It, the rings being secured together and sealed by a suitable binder so as to form a single unitary structure. In accordance with the invention the rings are iormed from a suitable magnetostrictive material such as' nickel and, when a varyin magnetic field is impressed thereon, the length of the rings changes slightly due to the magnetostrictive effect thereby causing corresponding variations in the width of the slot II. In this connection, it will be noted that the portions of each ring which are adjacent slot it are, in efiect, the ends of a straight piece of magnetostrictive metal and variations in the length of the metal piece cause changes in the width of slot ll.

Amagnetic field is impressed upon each of the rings ll by a coil I! which is wound longitudinally around the-cylindrical structure I! and has its ends connected to .the terminals it of a suitable alternating current source of a predetermined frequency. End caps I1 and I8 are secured to the respective ends of the cylindrical structure I! by a suitable sealing compound "A, such as a thermoplastic resin, and end cap It is provided with an opening for receiving the conduit ll through which fluid under pressure is admitted to the reservoir l0.

When coil I5 is energized by an alternating current of supersonic frequency, a magnetic field is established in the magnetostrictive structure I! and the strength of this field varies at the same frequency as the current applied to the coil. This causes corresponding variations in the width of the orifice H which modulates the fluid discharged therethrough, thus producing wave motion in the discharged fluid at the supersonic frequency of the alternating current applied to terminals I 6. This permits generation of supersonic waves of greater intensity than has heretofore been possible since the movement of the magnetostrictive member does not directly produce the supersonic pressure variations or waves but, rather, the movement of the magnetostrictive member merely controls the pressure which is originally produced by compression of the fluid inside the reservoir ll. During operation of the device, of course, there is relative movement between end caps l1, l8 and the cylindrical structure 2 but this movement is very small in magnitude and the resilient thermoplastic material I2A sealing the end caps can readily accommodate this small movement withtric annular rings i3. Each ring has a slot out allowing excessive leakage of fluid at the I cap 2|.

3 joints between cylinder structure 12 and end caps l1 and IS.

The modified construction shown by Figure 3 includesa cylindrical casing having end caps 2|, 22 secured thereto in any suitable manner. This structure defines a reservoir 23 to which fluid under pressure is admitted through a, conduit 24. End cap 22 is provided with a tapered orifice 25 with which cooperate a complementary tapered end portion 26 of a magnetostrictive rod 21. A support 28 is provided for the rod 21 and this support is secured in any suitable manner to the end cap 2| so that the rod is supported with the tapered portion 26 very closely space to the orifice 25.

A coil 29 is wound upon the magnetostrictive rod 21 and the leads of this coil are connected to binding posts 29a which are provided in end The binding posts 29a are connected by leads 30 to the respective terminals 3| of a suitable source of alternating current.

The structure of Figure 3 operates in substantially the same manner as that shown by Figures 1 and 2. When an alternating current is supplied to the coil 29, the tapered end 26 of the rod moves back and forth relative to the orifice 25 thereby periodically increasing and decreasing the size of this orifice at a frequency determined by the frequency of the alternating current supplied to terminals 3|. As a result, fluid discharged from orifice 25 is modulated and provides waves in the medium of the same frequency as the alternating current. That is to say, pressure variations or waves ar set up in the surrounding medium by the periodic increase and decrease in the size of the orifice which are then propagated through the surrounding medium. The frequency of vibration of the rod 21 may be made very high, if desired, so that high intensity ultrasonic waves of very high frequency and short wave length will be produced.

Although the invention has been described in connection with a preferred embodiment thereof, it will be understood that this description is not intended to limit the invention, the scope of which is defined by the appended claims.

We claim:

1. Apparatus tor producing wave motion in a gaseous medium at supersonic frequencies which comprises, in combination, a cylindrical structure formed from stacked slotted annular rings supersonic frequencies, causing corresponding variations in the width of said slot whereby the gas discharged from said orifice is modulated at supersonic frequencies.

2. Apparatus for producing wave motion in a gaseou medium at supersonic frequencies'which comprises, in combination, a cylindrical structure formed from stacked slotted annular rings of magnetostrictive material disposed in side by side arrangement, the slots therein being aligned to form a narrow orifice, mean for sealing the ends of said cylindrical structure, means for continuously supplying gas under pressure to the interior of said structure, and a coil wound toroidally about the wall of said cylindrical structure, said coil, when energized by alternating current of supersonic frequencies, causing corresponding variations in the width of said slot whereby the gas discharged from said orifice is modulated at supersonic frequencies.

FRANCIS WELDON CRAWFORD. JOHN S. IflRBY-SMITH.

REFERENCES CITED The following. references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 252,256 Rogers Jan. 10, 1882 1,488,789 Kinsley Apr. 1, 1924 1,526,319 Chubb Feb. 17, 1925 2,140,293 Kolb et a1 Dec. 13, 1938 FOREIGN PATENTS Number Country Date 101,140 Sweden Mar. 18, 1941 852,150 France Oct. 16, 1939 

